1. Field of the Invention
This invention relates to a radio communication system, more specially, gateway exchange methods for said system, and gateways, radio intelligent terminals and radio communication system utilized for said methods.
2. Description of the Prior Art
In recent years, the Internet Services such as WWW (World Wide Web) and etc. become so popular rapidly that the expansion of the computer network scales and the diversity of said connecting modes could be making advances.
In order to meet said progress, the gateways which connect intelligent terminals and servers via network are required to improve the processing ability and to increase the functions.
An example of the diversity of the connecting mode is a mobile computing. The mobile computing is a radio communication network which is able to be used by using a mobile terminal network such as portable phone network and by adding a radio communication function to an intelligent terminal even at the time of moving or even at a place impossible to connect directly with the computer network FIGS. 1 and 2 are conceptual view showing the communication mode adopting the above radio communication network.
FIG. 1 shows a constitution of the radio communication network with public network or in-house network for example, Local Area Network (LAN).
When an user executes an application in a terminal 1, the terminal 1 is connected with a server 6 via a radio base station 2, a network 3, and a gateway 4 or 5, and then the communication is established between the terminal 1 and the server 6. And the application is to be executed.
FIG. 2 shows an example of a radio communication network without passing through a network wherein gateways themselves have a server function, and which is operated in smaller area like an office than a place as shown in FIG. 1. Namely, the communication is established between the terminal 1 and the gateway 4 or 5 via radio base stations 2 or 10 and the application is to be executed.
In the radio communication network as described above, it is necessary to stop the operation of gateways temporarily for increasing functions of gateways to meet the change of networks and for operating the regular maintenance and so on. In order to continue the network operation on the stopped status of the gateway, it is necessary that the network is provided with the gateway exchange function, that is, a plural gateways are to be prepared as shown in FIGS. 1 and 2, and in case of deactivating the function of the gateway, the communication is to be established between the terminal and the server through the other gateway 5.
The outline of the communication protocol between the terminal and the gateway will be explained according to FIG. 7.
An application 71 in the terminal is a program such as WWW browser that an user operates directly. And an application 75 in the gateway (as shown in FIG. 2, the case of the gateway including server function is taken as an example) is a program for exchanging information with an application in the terminal, for example, a WWW server software.
A session layer protocol handler 72 (represented by a “S.L. protocol handler” hereinafter) is protocol means for offering a transfer controlling function which is common to various applications 71 and 75, for example, means such as a transfer processing of dividing into a transferable data and of transferring data per divided unit. A management entity means 73 (represented by a “M. entity means” hereinafter) is a program for managing system resources (such as a memory) which is used by a plural session processes generating at the data communication between a terminal and a server, and for managing processings over the whole system (for example, notice of a gateway exchange timing). A lower layer protocol handler 74 is a program and device for performing a communication control.
FIG. 31 shows a sequence of the communication mode in FIG. 2.
A S.L. protocol handler 3102 in a terminal 1 is in communication 3103 with a S.L. protocol handler 3104 in the gateway 4 in order to execute the application 3101. At this time, an gateway exchange instruction 3108 is inputted by an operator to a M. entity means 3105 in the gateway 4, and the M. entity means 3105 sends a disconnection notice 3109 to the S.L. protocol handler 3102 in the terminal 1 via the S.L. protocol handler 3104. Accordingly the S.L. protocol handler 3102 in the terminal 1 performs the disconnect display 3110 to the application 3101 or not, and then the execution of the application 3101 is suspended.
After the gateway 4 sends out the disconnection notice 3109, the gateway 4 gets into shutdown according to the operator's instruction or the function of the gateway 4. After that, the terminal 1, in order to re-execute the application 3101 thus suspended, requests the S.L. protocol handler 3102 to re-connect 3111 with the gateway 5 according to the address information in the terminal itself.
After the session 3112 is established between the S.L. protocol handler 3102 in the terminal 1 and the S.L. protocol handler 3106 in the gateway 5, the terminal 1 changes to be in communication 3113 with the gateway 5 and then it is possible to re-execute the application 3101 which has been suspended.
In the conventional technique as described above, however, there are some problems as follows.
In order to perform the gateway exchanging because of the shutdown of a gateway, the terminal has to store beforehand in the memory the address information about a plural gateways to be changeable objects. But the meaning that the information necessary only for exchanging the connection of gateway are always stored in the terminal is equivalent to the wasteful use of resources, and is not preferable for the terminal which has to be compact and provided with many functions.
And another problem is that, whenever that the network constitution changes according to the addition, the delete and etc. of severs or gateways, the gateway address information stored in the terminal have to be updated.
The method to solve the above problems, which is disclosed in the Japanese patent application No. 11-198675 filed in the name of this applicant, is to notify the exchange-destination gateway address to each terminal which is in communication with the exchange-original gateway at the time of shutdown. But this method is not available for the non-communicating terminals or the disconnecting terminals explained hereinafter.
The “non-communicating” terminal means the status that a terminal can always receive incoming signals from the other terminals even when the session (logical connection) is not established although the switch is turned on, that is to say, it is in the state of “standing by”. Meanwhile, the “disconnecting” terminal means the status that the terminal is switched off, or the status that the terminal cannot get into communication with a gateway because of standing outside the communication zone even though the switch is turned on.
In other words, there has not been any method for notifying the non-communicating or the disconnecting terminals of the address of the exchange-destination gateway. In the method disclosed in the Japanese patent application No. 11-198675, in case gateways changes when terminals are in the state of non-communicating or disconnecting, said terminals cannot receive the address of the exchange-destination gateway. Therefore the terminals cannot execute applications until the exchange-original gateway start up its operation again.
The present invention is proposed in order to solve the above problems, and provided with a radio communication system for notifying the address of the exchange-destination gateway and etc. to non-communicating or disconnecting terminals when the terminals starts the communication, in case the gateway exchange instruction was inputted by an operator. Therefore it is possible to avoid the wasteful use of the memory, to meet various changes of the network constitution easily, and to execute applications via the network at any time.